While there are a variety of technologies that may be used to connect a user to the Internet, many of which provide faster connection rates and better communication bandwidth than dial-up modems can provide as a connection mechanism, there are still those who use dial-up modem technology for connectivity. Many people do not have better connection options available to them, such as Asymmetric Digital Subscriber Line (ADSL), or they cannot afford the higher cost associated with them.
Almost all households and businesses, however, are still supplied with at least one telephone connection provided by a telecommunications network. Both incoming and outgoing calls are handled by a telephone company with whom the customer contracts to provide a well established set of services in accordance with a standard service level agreement (SLA). When modem users wish to connect their personal computer (PC) or computer to the Internet, they must usually dial a well-known telephone number to reach an Internet Service Provider (ISP) server through which connection to the Internet may be made. During data communications via the modem, the telephone company will be unable to route an incoming call to the user because the phone line will be busy due to the data communications traffic being received over the phone line.
In the case of ordinary voice conversation, the user is alerted to an incoming telephone call in the form of a pre-recorded operator voice message or special tone that alerts the user of a pending incoming call. This, however, is not available when the user has his telephone line busy with data traffic through a PC modem. The PC modem, moreover, is not able to interpret any voice message, nor is the user able to detect it, as the modem has exclusive control over the phone line.